1. Field of the Invention
The present invention relates to slicing of a veneer, and more specifically, to a knife for slicers for preventing the occurrence of rust (iron oxide) resulting from the reaction of tannic acid contained in sap with the iron in the knife.
2. Description of the Related Art
A knife for slicers is used to slice a veneer to be bonded to plywood and a veneer used as a material for laminated wood and the like from wood in such a manner that the knife is mounted on the tool post of slicers and the tool post is reciprocated. Conventional knives for slicers have such a structure that an edge steel is brazed to a base steel. In many cases, the base steel is formed of mild steel, and the edge steel is formed of alloy tool steel such as die steel and the like. When a veneer is sliced from a Japanese oak material or an oak material, there is caused a phenomenon called blue stain, whereby rust (ion oxide) is produced by the reaction of tannic acid contained in the sap of wood with the iron in the knives for slicers. When the blue stain occurs, treatment such as the bleaching of a stained veneer with oxalic acid and the like is necessary. Thus, there is required a measure for preventing the blue stain. In Japan, there have been employed various kinds of measures such as Teflon coating, hard chromium plating and paint coating to the surface of knives for slicers and the like as a blue stain preventing measure.
On the other hand, since a knife for slicers is a flat and large elongated the knife and used to accurately slice a veneer having a prescribed thickness from wood, it is preferable that the knife is composed of a material which does not produce rust by the reaction thereof with sap. Further, when the knife slices a considerable amount of veneers, wear, burr, chipping and the like are caused to the edge steel of the knife. To make the edge steel acute by removing the wear, burr, chipping and the like, therefor, it is subjected to a grinding job while it is held on an electromagnetic chuck by electromagnetic force. Since the grinding job is repeated periodically, the grinding job must be effectively executed by permitting the job to be set up easily.
Since the base steel of the conventional knives for slicers is formed of mild steel, the knives stain a veneer by the rust resulting from the reaction of the base steel with sap. Therefore, there must be taken a measure for bleaching a stained veneer or coating the surface of the edge steel to prevent the veneer from being stained.
An object of the present invention is to provide knives for slicers capable of preventing the stain of a veneer caused by rust produced to the surface of an edge steel and improving the durability of the knives.